1. Field of the Invention
This invention relates to a finisher for performing such additional works as sorting, binding, folding, and punching on recording material such as recording papers (hereinafter referred to briefly as "papers") outputted from an image forming apparatus such as a printing machine or copying machine. This invention, more particularly, relates to a finisher having the function of binding which comprises inserting papers from the image forming apparatus into a cover with a adhesive layer, which formed by coating a hot-melt adhesive on the inner face near a spine connecting a front board and a back board, and pasting the papers to the cover.
2. Description of the Related Art
Various finishers designed for performing various additional works on papers with an image formed surface, which are outputted from an image forming apparatus such as a printing machine or copying machine, have been proposed recently (U.S. patent application Ser. No. 08/821,444). The term "additional works" as used herein refers to various works such as sorting papers into sheaves of sheets, binding each of the sheaves with staples, doubling, creasing, or Z-folding and punching holes in the sheaf for filing.
Incidentally, the cover with a adhesive layer, which formed by coating a hot-melt adhesive on the inner face near a spine connecting a front board and a back board, has come onto the market. Further, the bookbinding technique, which produces a bound leaflet by inserting papers into the cover, giving the thermal processing to the adhesive layer of the cover, and pasting the cover and the papers, has been known. The bookbinding of this kind is referred to as "hot-melt binding".
Heretofore, the bookbinding by the hot-melt binding has been generally performed by manually aligning the edges of papers with a formed image, which have been outputted from an image forming apparatus, inserting the aligned papers into a hot-melt binding cover, and then placing the cover now holding the papers into an off-line heating device, namely a heating device installed separately from the image forming apparatus.
The production of bound leaflets by the hot-melt binding operation using the off-line heating device, however, necessitates manual works in numerous phases. That is to say, this operation has the disadvantage of poor operational efficiency because it calls for constant human attendance.
As stated in U.S. Pat. No. 4,586,640 and U.S. Pat. No. 5,213,317, a binding device, which makes a book by fixing a hot-melt type adhesive tape on the spine of a document, and which is connected to the image forming apparatus, has been heretofore proposed. A finisher, which is linked to an image forming apparatus, and which makes a book by using the commercially available hot-melt binding cover, has never existed to date.
When a finisher designed to attain automatic bookbinding by the use of the commercially available cover is developed at all, it has the problem that, since the allowable paper binding capacity of the cover is fixed, any attempt to bind in the cover such a number of papers as exceeds the capacity encounters an inconvenience.
In short, the number of papers to be stored in the cover and pasted thereto is limited because of a fixed spine width of the commercially available cover. When papers outputted from a copying machine or a printing machine are automatically conveyed into the cover, there is a possibility that the total of the papers exceeds the allowable paper binding capacity of the cover and infallible adhesion of the papers and the cover is not accomplished.
Further, in the process of bookbinding, the cover now holding the papers must be heated so as to uniformly melt the adhesive on the cover spine. In the conventional manual bookbinding operation, the possibility of this operation suffering from inferior adhesion of papers has been relatively small. Because the operator of the apparatus follows the rule of continuing the operation while making sure that the adhesion has been attained infallibly with due respect to the melting state of the adhesive and the temperature and the heating time of the thermal processing. In the automatic operation, the elaborate work of making sure that the adhesion has been attained infallibly deprives the significance of automation. The automation, therefore, is required to discern automatically whether or not the heating temperature is appropriate and whether or not the adhesive is melted uniformly.
Besides, the problem that the papers fall off the cover after the bookbinding operation is completed will ensue if the papers are not satisfactorily pasted to the spine of the cover. In this case, part of the adhesive adheres to the edges of the fallen papers and possibly renders the papers no longer usable. Further, the adhesive on the cover spine possibly melts partly and deprives itself of usability. In short, the problem of wasting the papers and the cover will inevitably arise.